Abstract: Congestion control in a communications network, e.g. an Internet Protocol (IP) network, is effected by controlling the egress rate of traffic from the output buffer of the system routers or switches. The traffic egressing from an output buffer is sampled at sequential intervals to determine a bit rate at each interval. An autocorrelation function is calculated from these samples and is used to provide an estimated statistical measure or parameter indicative of congestion and related to a long range dependence of the traffic. A calculation is then made as to whether an increase or a decrease in the buffer output rate would result in a decrease in the congestion parameter, and the buffer output rate is adjusted accordingly.

Abstract: A method for triggering an optical protection event in an optical layer of a network comprising the following steps: i) monitoring the optical performance of an optical signal transmitted within the optical layer of the network; ii) provisioning optical protection in the event the monitored optical performance falls below a first threshold level; and iii) triggering an optical protection event, in the event the monitored optical performance falls further to below a second threshold level. The monitoring step is performed within the optical layer of the network by using a proxy to determine an optical performance characteristic which corresponds to the transmission quality of electronic signals extracted from said optical layer signal.

Abstract: In a WDM network, a plurality of the channels are grouped together to form a packet. The format of one of the channels within the packet includes a packet header for providing routing or forwarding information for data on all of the channels of the group. The packet is routed or forwarded by a single port of a switching device in the nodes. This reduces usage of the ports of the switching device, and the invention enables an increase in the data transfer rate without altering the line equipment, as the individual channels still carry data at the same rate.

Abstract: In a photonic network, signals are degraded by passing through amplifiers. A maximum number of amplifiers may be traversed before regeneration is necessary. Regeneration (typically carried out in an optical cross-connect) involves relatively expensive hardware and is to be avoided if possible. An algorithm is set out which operates in two stages. In a first stage untenable paths are rejected and in a second stage the shortest path analyzes are carried out which maximizes the number of amplifiers interspersed between regenerative nodes thereby to minimize the use of regenerative nodes but ensures that all paths have regenerative nodes spaced at no more than a maximum interval of non-regenerative nodes.

Abstract: Congestion control in a communications network, e.g. an Internet Protocol (IP) network, is effected by controlling the egress rate of traffic from the output buffer of the system routers or switches. The traffic egressing from an output buffer is sampled at sequential intervals to determine a bit rate at each interval. An autocorrelation function is calculated from these samples and is used to provide an estimated statistical measure or parameter indicative of congestion and related to a long range dependence of the traffic. A calculation is then made as to whether an increase or a decrease in the buffer output rate would result in a decrease in the congestion parameter, and the buffer output rate is adjusted accordingly.

Abstract: In a photonic network, signals are degraded by passing through amplifiers. A maximum number of amplifiers may be traversed before regeneration is necessary. Regeneration (typically carried out in an optical cross-connect) involves relatively expensive hardware and is to be avoided if possible. An algorithm is set out which operates in two stages. In a first stage untenable paths are rejected and in a second stage the shortest path analyses are carried out which maximises the number of amplifiers interspersed between regenerative nodes thereby to minimise the use of regenerative nodes but ensures that all paths have regenerative nodes spaced at no more than a maximum interval of non-regenerative nodes.